Editing Slag (section)

===Modern uses===

==== Construction ====
Use of slags in the [[construction industry]] dates back to the 1800s, where [[Blast furnace slag|blast furnace slags]] were used to build [[roads]] and railroad ballast. During this time, it was also used as an aggregate and had begun being integrated into the [[cement industry]] as a [[Geopolymer cement|geopolymer]].<ref>{{Citation|last1=Netinger Grubeša|first1=Ivanka|title=4 – Application of blast furnace slag in civil engineering: Worldwide studies|date=2016-01-01|url=https://www.sciencedirect.com/science/article/pii/B978008100368800004X|work=Characteristics and Uses of Steel Slag in Building Construction|pages=51–66|editor-last=Netinger Grubeša|editor-first=Ivanka|publisher=Woodhead|language=en|isbn=978-0-08-100368-8|access-date=2021-11-27|last2=Barišić|first2=Ivana|last3=Fucic|first3=Aleksandra|last4=Bansode|first4=Samitinjay S.|editor2-last=Barišić|editor2-first=Ivana|editor3-last=Fucic|editor3-first=Aleksandra|editor4-last=Bansode|editor4-first=Samitinjay S.}}</ref>

Today, ground [[Ground granulated blast-furnace slag|granulated blast furnace slags]] are used in combination with [[Portland cement]] to create "[[slag cement]]". Granulated blast furnace slags react with [[portlandite]] ({{chem2|Ca(OH)2}}), which is formed during cement hydration, via the [[pozzolanic reaction]] to produce cementitious properties that primarily contribute to the later strength gain of concrete. This leads to concrete with reduced permeability and better durability. Careful consideration of the slag type used is required, as the high calcium oxide and magnesium oxide content can lead to excessive volume expansion and cracking in concrete.<ref>{{Cite journal|last1=Ortega-López|first1=Vanesa|last2=Manso|first2=Juan M.|last3=Cuesta|first3=Isidoro I.|last4=González|first4=Javier J.|date=2014-10-15|title=The long-term accelerated expansion of various ladle-furnace basic slags and their soil-stabilization applications|url=https://www.sciencedirect.com/science/article/pii/S0950061814007387|journal=Construction and Building Materials|language=en|volume=68|pages=455–464|doi=10.1016/j.conbuildmat.2014.07.023|issn=0950-0618}}</ref>

These hydraulic properties have also been used for soil stabilization in roads and [[Railroad construction|railroad constructions]].<ref>{{cite book|last1=Grubeša|first1=Ivanka Netinger|chapter=Chapter 7: Diverse Applications of Slags in the Construction Industry|date=2021-08-04|url=https://pubs.rsc.org/en/content/chapter/bk9781788018876-00194/978-1-78801-887-6|title=Metallurgical Slags|pages=194–233|language=en|access-date=2021-11-27|last2=Barišić|first2=Ivana|series=Chemistry in the Environment|doi=10.1039/9781839164576-00194|isbn=978-1-78801-887-6|s2cid=238965391}}</ref>

Granulated blast furnace slag is used in the manufacture of high-performance concretes, especially those used in the construction of bridges and coastal features, where its low permeability and greater resistance to chlorides and sulfates can help to reduce corrosive action and deterioration of the structure.<ref>{{Cite web|title=High Performance Cement for High Strength and Extreme Durability by Konstantin Sobolev|url=http://www.geocities.com/ResearchTriangle/Forum/1657/Cement/high_performance_cement.html|archive-url=https://web.archive.org/web/20090803185555/http://geocities.com/ResearchTriangle/Forum/1657/Cement/high_performance_cement.html|archive-date=2009-08-03|access-date=2009-06-18}}</ref>{{ugc|reason=Geocities was a personal web hosting service|date=March 2024}}

Slag can also be used to create fibers used as an insulation material called ''[[slag wool]]''.

Slag is also used as aggregate in [[asphalt concrete]] for [[Road surface|paving roads]]. A 2022 study in Finland found that road surfaces containing [[ferrochrome slag]] release a highly abrasive dust that has caused car parts to wear at significantly greater than normal rates.<ref>{{cite web |date=20 September 2022 |title=Autojen jakohihnojen rikkoutumisen taustalla ferrokromikuonan eli OKTO-murskeen aiheuttama kuluminen |url=https://www.gtk.fi/ajankohtaista/autojen-jakohihnojen-rikkoutumisen-taustalla-ferrokromikuonan-eli-okto-murskeen-aiheuttama-kuluminen/ |access-date=20 September 2022 |website= |publisher=Geological Survey of Finland |language=fi}}</ref>

==== Wastewater treatment and agriculture ====
Dissolution of slags generate alkalinity that can be used to precipitate out metals, sulfates, and excess nutrients (nitrogen and phosphorus) in wastewater treatment. Similarly, ferrous slags have been used as soil conditioners to re-balance [[soil pH]] and [[fertilizer]]s as sources of calcium and magnesium.<ref>{{Citation|last1=Gomes|first1=Helena I.|title=Chapter 8: Environmental Applications of Slag|date=2021-08-04|url=https://pubs.rsc.org/en/content/chapter/bk9781788018876-00234/978-1-78801-887-6|work=Metallurgical Slags|pages=234–267|language=en|access-date=2021-11-27|last2=Mayes|first2=William M.|last3=Ferrari|first3=Rebecca|series=Chemistry in the Environment|doi=10.1039/9781839164576-00234|isbn=978-1-78801-887-6|s2cid=238967817}}</ref>  

Because of the slowly released phosphate content in [[phosphorus]]-containing slag, and because of its [[Liming (soil)|liming]] effect, it is valued as fertilizer in gardens and farms in steel making areas. However, the most important application is construction.<ref>{{Cite journal|last1=O'Connor|first1=James|last2=Nguyen|first2=Thi Bang Tuyen|last3=Honeyands|first3=Tom|last4=Monaghan|first4=Brian|last5=O'Dea|first5=Damien|last6=Rinklebe|first6=Jörg|last7=Vinu|first7=Ajayan|last8=Hoang|first8=Son A.|last9=Singh|first9=Gurwinder|last10=Kirkham|first10=M. B.|last11=Bolan|first11=Nanthi|date=2021|title=Production, characterisation, utilisation, and beneficial soil application of steel slag: A review|url=http://dx.doi.org/10.1016/j.jhazmat.2021.126478|journal=[[Journal of Hazardous Materials]]|volume=419|pages=126478|doi=10.1016/j.jhazmat.2021.126478|pmid=34323725|bibcode=2021JHzM..41926478O |issn=0304-3894}}</ref>

==== Emerging applications ====
Slags have one of the highest carbonation potential among the industrial alkaline waste due their high calcium oxide and magnesium oxide content, inspiring further studies to test its feasibility in {{chem2|CO2}} capture and storage ([[CCS and climate change mitigation|CCS]]) methods (e.g., direct aqueous sequestration, dry gas-solid carbonation among others).<ref>{{Cite journal|last=Doucet|first=Frédéric J.|date=2010-02-01|title=Effective CO2-specific sequestration capacity of steel slags and variability in their leaching behaviour in view of industrial mineral carbonation|url=https://www.sciencedirect.com/science/article/pii/S0892687509002313|journal=[[Minerals Engineering]]|series=Special issue: Sustainability, Resource Conservation & Recycling|language=en|volume=23|issue=3|pages=262–269|doi=10.1016/j.mineng.2009.09.006|issn=0892-6875}}</ref><ref>{{Cite journal|last1=Romanov|first1=Vyacheslav|last2=Soong|first2=Yee|last3=Carney|first3=Casey|last4=Rush|first4=Gilbert E.|last5=Nielsen|first5=Benjamin|last6=O'Connor|first6=William|date=2015|title=Mineralization of Carbon Dioxide: A Literature Review|url=https://onlinelibrary.wiley.com/doi/abs/10.1002/cben.201500002|journal=ChemBioEng Reviews|language=en|volume=2|issue=4|pages=231–256|doi=10.1002/cben.201500002|osti=1187926|issn=2196-9744}}</ref> Across these CCS methods, slags can be transformed into [[precipitated calcium carbonate]]s to be used in the plastic, and concrete industries and [[Leaching (chemistry)|leached]] for metals to be used in the electronic industries.<ref>{{Cite journal|last1=Ragipani|first1=Raghavendra|last2=Bhattacharya|first2=Sankar|last3=Suresh|first3=Akkihebbal K.|date=2021|title=A review on steel slag valorisation via mineral carbonation|url=http://xlink.rsc.org/?DOI=D1RE00035G|journal=Reaction Chemistry & Engineering|language=en|volume=6|issue=7|pages=1152–1178|doi=10.1039/D1RE00035G|s2cid=236390725|issn=2058-9883}}</ref>

However, high physical and chemical variability across different types of slags results in performance and yield inconsistencies.<ref>{{Cite journal|last1=Brand|first1=Alexander S.|last2=Fanijo|first2=Ebenezer O.|date=2020-11-19|title=A Review of the Influence of Steel Furnace Slag Type on the Properties of Cementitious Composites|journal=[[Applied Sciences]]|language=en|volume=10|issue=22|pages=8210|doi=10.3390/app10228210|issn=2076-3417|doi-access=free|hdl=10919/100961|hdl-access=free}}</ref> Moreover, [[stoichiometric]]-based calculation of the carbonation potential can lead to overestimation that can further obfuscate the material's true potential.<ref>{{Cite journal|date=1956|title=Some Effects of Carbon Dioxide on Mortars and Concrete|url=http://dx.doi.org/10.14359/11515|journal=ACI Journal Proceedings|volume=53|issue=9|doi=10.14359/11515|issn=0002-8061}}</ref> To this end, some have proposed performing a series of experiments testing the reactivity of a specific slag material (i.e., [[Solvation|dissolution]]) or using the [[Rigidity theory (physics)|topological constraint theory]] (TCT) to account for its complex chemical network.<ref>{{Cite journal|last1=La Plante|first1=Erika Callagon|last2=Mehdipour|first2=Iman|last3=Shortt|first3=Ian|last4=Yang|first4=Kai|last5=Simonetti|first5=Dante|last6=Bauchy|first6=Mathieu|last7=Sant|first7=Gaurav N.|date=2021-08-16|title=Controls on CO2 Mineralization Using Natural and Industrial Alkaline Solids under Ambient Conditions|url=https://doi.org/10.1021/acssuschemeng.1c00838|journal=ACS Sustainable Chemistry & Engineering|volume=9|issue=32|pages=10727–10739|doi=10.1021/acssuschemeng.1c00838|s2cid=238670674}}</ref>